DESCRIPTION (applicant's abstract): The innovative use of AAV vector technology is proposed to develop milestones essential for the safe treatment of anemia secondary to chronic renal failure in cats. An A.AV-FeEPO vector has been constructed. The initial, in vitro, study will determine whether this vector can achieve FeEPO expression, and will also validate a HuEPO ELISA kit to measure FeEPO. This vector will then be administered IM to cats to investigate gene expression, in vivo. The transduced skeletal muscle will then be surgically excised to determine whether FeEPO expression is abolished. Transduction of tissues distant to the injection site will be determined by using PCR. Two studies will be performed to find the optimum method of FeEPO expression in feline patients with anemia. Firstly, AAV-FeEPO will be repeatedly administered at low doses to determine if this results in predictable incremental FeEPO expression. Finally, an AAV-FeEPO vector controlled by the Tet-On system will be constructed. Oral doxycycline will be administered at different doses (to demonstrate dose-dependent FeEPO expression) intermittently (to ascertain whether FeEPO expression can be "turned-on and off"). Cell mediated, and humoral immune responses against the vector will be measured in these cats. PROPOSED COMMERCIAL APPLICATION: Feline erythropoietin cDNA will be incorporated in an adeno-associated virus vector (AAV-FeEPO) and administered to cats with chronic renal failure and other types of erythropoietin responsive anemia. Expression of the feline erythropoietin cDNA will be controlled by a tetracycline regulatory element. This vector construct may be sold as a veterinary only pharmaceutical.